001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package org.apache.hadoop.io;
020    
021    import java.io.DataInput;
022    import java.io.DataOutput;
023    import java.io.IOException;
024    
025    import org.apache.hadoop.classification.InterfaceAudience;
026    import org.apache.hadoop.classification.InterfaceStability;
027    
028    /**
029     * Writable for Double values.
030     */
031    @InterfaceAudience.Public
032    @InterfaceStability.Stable
033    public class DoubleWritable implements WritableComparable<DoubleWritable> {
034    
035      private double value = 0.0;
036      
037      public DoubleWritable() {
038        
039      }
040      
041      public DoubleWritable(double value) {
042        set(value);
043      }
044      
045      public void readFields(DataInput in) throws IOException {
046        value = in.readDouble();
047      }
048    
049      public void write(DataOutput out) throws IOException {
050        out.writeDouble(value);
051      }
052      
053      public void set(double value) { this.value = value; }
054      
055      public double get() { return value; }
056    
057      /**
058       * Returns true iff <code>o</code> is a DoubleWritable with the same value.
059       */
060      @Override
061      public boolean equals(Object o) {
062        if (!(o instanceof DoubleWritable)) {
063          return false;
064        }
065        DoubleWritable other = (DoubleWritable)o;
066        return this.value == other.value;
067      }
068      
069      @Override
070      public int hashCode() {
071        return (int)Double.doubleToLongBits(value);
072      }
073      
074      @Override
075      public int compareTo(DoubleWritable o) {
076        return (value < o.value ? -1 : (value == o.value ? 0 : 1));
077      }
078      
079      @Override
080      public String toString() {
081        return Double.toString(value);
082      }
083    
084      /** A Comparator optimized for DoubleWritable. */ 
085      public static class Comparator extends WritableComparator {
086        public Comparator() {
087          super(DoubleWritable.class);
088        }
089    
090        @Override
091        public int compare(byte[] b1, int s1, int l1,
092                           byte[] b2, int s2, int l2) {
093          double thisValue = readDouble(b1, s1);
094          double thatValue = readDouble(b2, s2);
095          return (thisValue < thatValue ? -1 : (thisValue == thatValue ? 0 : 1));
096        }
097      }
098    
099      static {                                        // register this comparator
100        WritableComparator.define(DoubleWritable.class, new Comparator());
101      }
102    
103    }
104